Boiler



BOILER April 2s, 1942. 2'

Filed sept. 21, 1939 2 Sheets-Sheet l Mvg/woes y MN o im. fm 6%@ ma AM JM H April 28, 1942. J. J. GROENEMA ETAL 2,281,431

BOILER Filed sept. 21, 1939 2 sheets-Sheet 2 A Troni/5X5 Patented Apr. 28, 1942 asian BOILER Jan J. Groenema, The Hague, and Hermannus van Tongeren, Heemstede, Netherlands Application September 21, 1939, Serial No. 295,384 In Germany September 21, 1938 3 Claims.

Our invention relates to boilers, more especially for central heating systems, comprising a 'water-jacketed furnace and a heat exchanging apparatus mounted in serial relation with the furnace in such a manner that the hot gases from the combustion chamber of the furnace are compelled, on their way to the chimney, to transmit part of their heat to said apparatus.

In known boilers of this type, the heat exchanging apparatus comprises a tubular system formed by a nest of narrowly spaced water tubes arranged immediately opposite the passage through which the hot gases from the combustion chamber' of the furnace flow towards said system. Owing to this arrangement, the hot gases flowing from the furnace into said apparatus are unduly cooled and cannot be burnt completely.

It is well known in the art that economical combustion requires a predetermined ratio between the capacity of the combustion chamber and the amount of coal burnt per unit of time. With a combustion chamber of given capacity, the heating surface is practically xed, i. e. said surface can only be varied between vary narrow limits, whatever shape be given to said chamber.

Our invention is based upon the discovery that combustion can be appreciably improved by dividing the combustion chamber into two separate chambers, so as to increase the heating surface to furnace capacity ratio.

Thus, in accordance with our invention, the heat exchanging apparatus comprises a spacious combustion chamber, which has water cooled walls and accommodates the tubular system referred to in such a manner that said system is mounted in the vicinity of the chamber outlet and occupies only the smaller part of the chamber, leaving the greater part of the chamber Void. This construction ensures appreciably increased efficiency of the combustion gases.

In order that the combustion gases may ow through the heat exchanging apparatus at substantially uniform speed, a baffle or partition may be provided in said combustion chamber in such a manner as to gradually reduce its cross-sectional area in a direction from inlet to outlet, in which case the tubular system is preferably disposed on either side of said baiile.

In order that our invention may be more fully understood and carried into practice, we shall now proceed to describe it in further detail with reference to the annexed drawings, on which:

Fig. 1 is a longitudinal sectional elevation of a boiler constructed in accordance withour invention,

Fig. 2 is a plan sectional elevation along the line IIe-II in Fig. 1, and

Fig. 3 is a transverse vertical sectional tion along the line III- III in Fig. 1.

is illustrated, the boiler comprises a vertical, cylindrical, water jacketed furnace or re'box I and, in serial relation therewith, a heat `exchanging apparatus 2 adapted to be heated by the combustion gases from the furnace. Said parts are mounted on a hollow base 3, which is divided by a vertical partition 4 into two compartments 5, 6. Compartment 5 is located vertically below the fire box and may accommodate a feed screw (not shown), by means of which coal can be fed into the fire box through an opening 8, through which said compartment communicates with the combustion chamber 9 inside the fire box. Said opening 8 is enclosed by a water cooled ring ID.

The re boX I is provided with a front door II and, opposite said door, with an opening I2, through which the combustion gases from the chamber 9 flow into a second combustion chamber I3 forming part of the heat exchanging apparatus 2.

The apparatus Z comprises four parallel, horizontal headers I4, I5, IIS and I'I of rectangular cross-section. Headers I4 and I5 communicate with the top portion of the water jacket of the rire box I through substantially diametrically opposed, tangential openings 32 thereof, whereas the headers I6 and II, which are located vertically below the headers I4 and I5, respectively, communicate with the lower portion of the water jacket in a similar manner not shown as do the top headers I4, I5. As shown, headers I4 and I5 communicate through horizontal, transverse water tubes I8 interconnected by webs 29 so as to form an impervious top wall, and headers I6 and I'I communicate through horizontal, transverse water tubes I9. The rearmost tubes of the series of tubes I8 and i9 communicate through vertical water tubes 20 interconnected by Webs 29a so as to form the impervious rear wall of the heat exchanging apparatus 2.

The headers I4 and I6 communicate through two series of vertical water tubes 2I disposed in staggered relation to one another, and the headers I5 and I'I communicate in a similar manner by vertical water tubes 22. The tubes 2I, 22 thus form linings of the side Walls of the a paratus 2. They are provided, at a small diseleva- 'tance above the headers I6 and II, respectively,

with horizontal bends v23 and 24, respectively,

which extend through substantially the full width of the heat exchanging apparatus so as to virtually form a kind of bottom. Provided below said bottom tubes 23, 24 is a small box 25, which, together with the compartment 6 and an inclined baie 26, serves to reverse the direction of iiow of the hot gases on their way from the opening I2 to the flue 21, through which the heat exchanging apparatus is connected with the stack (not shown) The sill of opening I2 is formed by a fire bridge 28, which preferably is provided with passages (not shown), through which preheated secondary air is supplied so as to ensure complete combustion of the gases in the chamber I3.

The cold water feed pipe is designated by 3B, the hot water discharge nozzle by 3 I.

Water tubes 32 are provided for cooling the baffle 26.

It may still be remarked that the substantially A horizontal position of the tubes 23, 24 is of essential importance with a View to the transmission thereto of heat from the hot gases, the general direction of flow of which is at substantially right angles thereto, and also with a view to obtaining a spacious, void combustion chamber in serial relation with the primary combustion chamber S.

What we claim is:

l. In a boiler for a central heating system, a water-jacketed furnace, walls forming a chamber adjacent said furnace, walls extending from near the top of said furnace and said chamber establishing a passageway therebetween, a continuous tubular heat exchange system lining most of the wall area of said chamber, said heat exchange system including a lower bank of tubes adjacent the lowermost wall of said chamber, said system occupying only a minor portion of the space of said chamber, means defining a flue opening in a wall of said chamber, the upper extremity of the opening lying above al1 of the tubes constituting said lower bank, and a baille extending inwardly and downwardly from the uppermost point of said means dening a flue opening to a point below at least some of the tubes constituting said lower bank and below said flue opening, whereby burning gases issuing from the furnace through the passageway will be caused to contact the upper runs of the heat exchange system in the chamber and then beforeissuing through said ue opening to contact the lower bank of tubes.

2. In a boiler for a central heating system, a water-jacketed furnace, walls forming a chamber adjacent said furnace, walls near the top of said furnace and said chamber establishing a passageway therebetween, a continuous tubular heat exchange system lining those walls of said chamber which lie in planes parallel the axis of the passageway, said heat exchange system including a lower bank of tubes adjacent the lowermost wall of said chamber, said system occupying only a minor portion of the space of said chamber, a wall of said chamber lying at right angles to the axis of said passageway having a flue opening therein extending thereacross, the upper extremity of said opening lying above all of the tubes constituting said lower bank, and a baffle coextensive in width with said opening extending inwardly and downwardly from the uppermost defining edge thereof to a point below at least some of the tubes constituting said lower bank and below the lower defining edge of said flue opening, whereby burning gases issuing from the furnace through the passageway first will be caused to contact the upper runs of the heat exchange system in the chamber and then before issuing through said flue opening to contact the lower bank of tubes.

3. In a boiler as claimed in claim l, means establishing communication between said tubular heat exchange system and the water jacket of said furnace.

JAN J. GROENEMA. HERMANNUS VAN TONGEREN. 

